Craftsmen Edger Problem

Hi--my name is Jay Worrall, and I am trying to solve a problem for my mother-in-law.  She has a craftsmen 9.0" 3.0 hp edger trimmer, model # 536.797520.  Oil is leaking out of the right side as you're "driving" it, left side if you are facing it.  I am not certain the part it is leaking from.  Although it looks like an air filter, roughly the size and thickness of your hand, and clearly oil/something is supposed to cycle through it.  It is silver in color, apparently made of aluminum, and has several "exhaust" type holes prefabricated in the side of it in a roughly circular pattern.  Whenever the edger is running, oil starts leaking out of these holes.  I have not left the edger on long enough to see if this stops, or if it will keep dripping.  We recently changed the oil in this edger, and it could be that in tipping the machine, oil got into an area it would not normaly have gotten into, and it simply needs to burn off.  Please let me know if this is a chronic problem, if there is a part I can replace, or if this is something else.  Thanks!